Some of them are for entertainment -- designed to control A/V equipment in your living room. Others control household appliances, functions on your computer, or even expensive corporate security systems.

For now, most remote control apps operate over the Internet, or via a wi-fi or Bluetooth link between your iPhone and another device. But one company is developing an infrared iPhone accessory, which will open the doors for even more remote control applications.

It's conceivable that, with these apps and accessories, an iPod touch could replace the fanciest of universal remotes, and have the bonus of shipping with a Web browser and all the other apps on the App Store.

Here's an updated version of our list of iPhone remote control apps. Let us know if we missed any good ones.

DVR

More TV providers are releasing iPhone apps to use as DVR remotes. Recently, Comcast published an app that allows some of its digital cable subscribers program their DVRs remotely. And free apps from DirecTV, DISH Network, and AT&T let you program your digital video recorder from anywhere.

Zipcar rental car

The free Zipcar app lets you find and book rental cars. But the impressive part is that you can also use your iPhone to unlock the car or make its horn beep.

Home lights and automation system

A recent Apple commercial highlights this app for the Schlage LiNK home automation and security systems. You can watch your doors, lock and unlock them, turn lights on and off, etc.

Blu-ray Discs

Several Blu-ray discs include Internet features that can be accessed via iPhone apps. For example, the free "pocket BLU" app can act as a remote for Blu-ray discs that support "pocket BLU" -- including "Bruno," "Funny People," other movies. Features include controlling playback, browsing through chapters, the soundtrack, etc.

Presentations

Desktop PC or Mac

This one takes a little tinkering, but free VNC -- "virtual network computing" -- remote desktop software on your computer (Mac, PC, Linux, etc.) will let you view and control it from anywhere, provided it's turned on and hooked up to the Internet.

Photoshop

Apple TV

Apple's free Remote software also controls the Apple TV set-top box, if you have one of those.

A recent update adds a nifty feature that lets you use your iPhone's multi-touch screen as a "gesture pad" to scoot around the Apple TV display. This is much easier than using the small, plastic remote that came with Apple TV.

You can also use the Boxee remote app to remote-control Boxee, if you've loaded that onto your Apple TV.

Sonos Home Stereo

If you have a Sonos multi-room sound system -- especially the popular, newish S5 -- your iPhone is a remote via the free Sonos Controller app.

Pro audio software

The ProRemote ($99.99) and ProRemote Lite ($35.99) act as sliders and other controls for pro audio editing software, including ProTools and Apple's Logic software.

Burglar Alarm

CPI Security customers can use a free iPhone app (with additional service) to monitor their home security system, turn it on and off, see activity history, etc.

X-Plane Flight Simulator

Sort of like how Nintendo's DS has a touch-sensitive second screen that often controls what's happening on the first screen, this will let you control and observe some of your flight simulator's features -- on your computer -- using the iPhone as a smaller, second screen.